diff --git a/tacker/glance_store/store.py b/tacker/glance_store/store.py
index 10e10b0d1..4b234fe51 100644
--- a/tacker/glance_store/store.py
+++ b/tacker/glance_store/store.py
@@ -150,6 +150,6 @@ def _add_basic_auth(request, username, password):
 
     This function adds basic authentication information to a urllib request.
     """
-    auth_str = base64.encodestring(('%s:%s' % (
+    auth_str = base64.encodebytes(('%s:%s' % (
         username, password)).encode()).decode().strip()
     request.add_header('Authorization', 'Basic %s' % auth_str)
diff --git a/tox.ini b/tox.ini
index fdab5b433..33ce79079 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py38,py36,pep8,docs
+envlist = py39,py38,py36,pep8,docs
 minversion = 3.1.1
 skipsdist = True
 ignore_basepython_conflict = True
@@ -40,6 +40,10 @@ commands = oslo_debug_helper {posargs}
 basepython = python3.6
 commands = oslo_debug_helper {posargs}
 
+[testenv:debug-py39]
+basepython = python3.9
+commands = oslo_debug_helper {posargs}
+
 [testenv:pep8]
 deps = -r{toxinidir}/doc/requirements.txt
        -r{toxinidir}/test-requirements.txt